Flow Visualization Study of Secondary Flow in a Corner

摘要

An experimental investigation has been made of secondary flow in a 90 degree corner. The tests were run in a water tunnel at low speed (approximately 0.3 ft. per sec.) with emphasis on an attempt to visualize the embedded vortices in the laminar flow. The Reynolds number range was 11,000 to 52,500 per foot; the corner model was 9.75 in. wide by 48 in. long. The model was aligned in the tunnel so that no streamwise pressure gradient was present. Flow visualization was by means of hydrogen bubbles and dye. None of the streak-line examined with either the bubbles or the dye showed any indication of the presence of secondary motion in the first 18 inches of the corner. This is not believed to be conclusive since the vortices may exist at other distances along the corner (the limit here was imposed by the flow visualization apparatus used) or may be poorly developed in the initial length examined. (Author)